The invention relates to a drilling tool, in particular a reamer and a method for surface processing of an inner walling of a pre-drilled workpiece core bore.
From DE 10 2013 004 105 A1 a generic reamer is known which can for example be used in vehicle construction for fine processing of an inner walling of a cylinder head bore in order to improve the surface quality and shape and dimensional accuracy of the bore. At its outer circumference the reamer has at least one main blade with a radially outer cutting edge which extends spirally along the drill body longitudinal axis up to a cutting corner arranged at the drill tip. At the front-side blade corner the main blade transitions into a groove blade which is oriented transversely relative to the drill body-longitudinal axis.
With the above reamer the surface processing of the core bore is performed with the following process steps: in a first pre-processing step the reamer is inserted into the core bore with a low rotational speed and a feed speed adjusted to the rotational speed, whereby the groove blade generates a spiral groove in the inner walling of the core bore. In the fully inserted state the main blade, which adjoins the groove blade, is already fully engaged with the spiral groove. In the subsequent second processing step the main blade of the reamer can, through rotation, effect a circumferential material removal without axial feed.
The two processing steps have to be performed successively which is time consuming. Moreover, in the second processing step the circumferential material removal performed with the main blade is associated with a high cutting stress. Therefore in order to avoid premature tool failure the above reamer is preferably used for processing softer materials, for example aluminum.